Fuel feeding &amp; charge forming apparatus

ABSTRACT

A carburetor and fuel feeding arrangement for internal combustion engines which includes a substantially horizontally extending mixing passage with venturi and a fuel chamber located below said passage. A diaphragm constitutes an upper wall of the fuel chamber and is adapted to operate a fuel inlet valve. The diaphragm also forms a lower wall of a chamber which communicates with the atmosphere. A main fuel discharge orifice is positioned substantially on the center line of the diaphragm. A slow fuel passage branches from a fuel passage connecting the fuel chamber and the orifice and communicates with secondary orifices. Means is provided for discharging into the fuel passages the vapor generated when the apparatus is tilted to extreme positions or inverted. Means between the main fuel passage and the slow fuel passage is provided for preventing the flow of air from the main orifice to the secondary orifices during idling or slow speed motion of an engine.

United States Patent n91 1111 3,825,237

Aoyama et al.- July 23,1974

FUEL FEEDING 8; CHARGE FORMING APPARATUS Primary Examiner-Tim R. Miles[75] Inventors: Taizo Aoyama, Tokyo; Katsuya Attorney, Agent orFirmStevens, Davis, Miller &

Kamosawa, Yokosuka, both of Mosher Japan [73] Assignee: NipponCarbureter Co. Ltd'., Tokyo, ABSTRACT I apan A carburetor and fuelfeeding arrangement for inter [22] Filed: Nov. 22, 1971 nal combustionengines which includes a substantially 1 horizontall extendin mixin assae with venturi 21 Y 8 g P g 1 200890 and a fuel chamber located belowsaid passage. A diaphragm constitutes an upper wall of the fuel chamber[30] Foreign Application Priority Data "and is adapted to operate a fuelinlet valve. The dia- Oct. 24, 1970 Japan 45-105982 "P a forms a lowerWall of a chamber which I communicates with the atmosphere. A main fueldis- [52] US. Cl..; 261/35, 261/69 A, 261 /DIG 68 charge orificeis'positionecl substantially on the center 51 int. Cl......- F02m 17/04a line of the diaphragm A Slow fuel passage branches [58] Field ofSearch 261/DlG. 68, 35,69 A f a fuel passage connecting the fuel chamberand 1 the orifice and communicates with secondary orifices. [56] Refer nCit d 7 Means is provided for discharging into the fuel pas- UNITEDSTATES PATENTS t sages the vapor generated when the apparatus is tilted1,897,742 2/1933 Viel 26l/DlG 68 extreme posmons or Inverted Meansbetween 1 261mm 68 fgmain fuel passage and the slow fuel passage is pro-261mm: 68 Y vided for preventing the flow of air from the main ori-"Jul/1316.68; --fice to the secondary orifices during idling or slow2,068,938 1/1937 Viel 2,823,905 2/1958 Brown 2,84l,372 7/1958 Phillips3,235,238 2/1966 Martin et al. 261/DIG. 68 p motion O an engine- FOREIGNPATENTS OR APPLICATIONS I 4 Chin's, 7 Drawing Figures 936,994 3/1965Great Britain 261/DIG. 68

. I i I v SHEET 10$ 2 FIG.1

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SHEEF 2 BF 2 4 FIG.4

FUEL FEEDING &CHARGE FORMING APPARATUS ternal combustion engine in allpositions of the engine.

This invention pertains more especially to a diaphragm type carburetorfor use with internal combustion engines for motor-cars as well asinternal combustion engines suitable for powering chain saws, lawnmowers, outboard marine engines and the like which are operated ininverted positions as well as positions of extreme tilt.

Carburetors for use with chain saw engines and the like have a mixingpassage, a main fuel nozzle or orifice for delivering fuel for highspeed operation into a venturi in the passage and secondary orificesopening into the mixing passage downstream of the venturi for deliveringfuel into the mixing passage for engine idling or slow speed operation.g

Fuel for the main fuel orifice and the secondary orifices is suppliedfrom a fuel chamber inthe carburetor through channel means. One wall ofthe fuel chamber is defined by a flexible diaphragm which underabsorption or reduced pressures in the mixing passage, controls a fuelinlet valve for regulating the flow of fuel from a supply into the fuelchamber. In such arrangement, when the carburetor is in certainpositions of tilt or inverted positions, the head of fuel in the fuelchamber is affected by the weight of the diaphragm so that pressure offuel to be supplied to the orifices will be liable to variation. Thevariation in pressure of fuel may be theoretically prevented bysubstantially eliminating the weight of the diaphragm, but practically,this is impossible.

, This invention relates to a diaphragm type carburetor or fuel feedingarrangement wherein the fuel chamber is located below the diaphragm.

In the carburetor embodying the present invention, the relation betweenthe main fuel discharge orifice and the diaphragm should be exactly orapproximately given by the following formula in order to ensure a supplyof the required quantity of fuel from the main fuel orifice irrespectiveof positions of tilt or angular posi-' tion of the carburetor;

h W/A wherein h the distance between the center of the underside of thediaphragm and the inlet of the main fuel discharge orifice A theeffective area of the diaphragm W the weight of the diaphragm d) thespecific gravity of fuel Another object of this invention is to providea diaphragm type carburetor wherein the main fuel orifice opens into thefuel chamber at the center of the diaphragm or at a region close to thecenter of the diaphragm to ensure a supply of the required quantity offuel irrespective of carburetors angular positions. Another object ofthis invention is to provide a carburetor which discharges into the mainfuel passage the vapor of fuel generated by cavitation or percolationinto the fuel chamber when the carburetor is tilted or inverted so thatthe carburetor is free from suffering an insufficience of fuel due tothe low level of fuel in the fuel 2 chamber occurring at the time ofrestoring it to the normal position.

The other object of this invention is to provide a carburetor whichprevents flow of air through the fuel passage from the main fuel orificeto the secondary orifices, this flow of air being caused by strongreduced pressure in the mixing passage during idling and slow speedoperation of an engine. I

Other objects and advantages of this invention will be readilyappreciated as the same becomes better understood by reference'to thefollowing detailed description when considered in connection with theaccompanying drawings wherein: 7

FIG. 1 is a top plan view of an apparatus embodying the invention; FIG.2 is afragmentary front elevation view of the appratus shown in FIG. 1;

HG. 3 is a cross sectional view taken substantially along the line 33 ofFIG. 1;

FIG. 4 is a fragmentary cross sectional view substantially along line4--4 of FIG. 1;

FIG. 5 is a fragmentarycross sectional view taken taken substantiallyalong line 5-5 of FIG. 2;

FIG. 6 is an enlarged fragmentary view of FIG. 3;: and

1 FIG. 7 is a fragmentary view of FIG. 4, showing the apparatus of thisinvention in inverted position.

Referring to the drawings, a carburetor body 10 is provided with ahorizontally extending mixing passage 11. This passage 11 includes aventuri 12, an air inlet region 13 and a mixture outlet region 14. Thecarburetor body 10 is provided at one end with a mounting flange 15which is adapted to be secured to a boss portion formed on an enginecrankcasetnot shown) and the air inlet end of the carburetor body 10 isprovided with a flange 16 for mounting an aircleaner (not shown). I

A choke valve 17 for controlling the admission or air into the air inletregion is disposed in the air inlet region l3of the mixing passage 11,and mounted on a choke shaft 18 supported in holes formed in bosses 19and 20 of the body 10. Outer portion of the shaft 18 extending outwardlyfrom the body 10 has an arm 22 mounted thereon, the arm having a-chokewireterminal 2 1 for manipulating the choke valve 17. v v

. Disposed in the mixture outlet region 14 of the mixing passage 11 is athrottle valve 23 mounted on a throttle shaft 24 supported in holesformed in bosses 25 and 26 of the body 10. Secured to the end of shaft24 is a L-shaped arm 28 with throttle wire terminal 27 for manipulatingthe throttle valve 23. The body 10 is provided with a projection 29having a threaded opening to receive an adjusting screw 30, the end ofscrew 30 being engaged with a portion of the arm 28 to limit the closingmovement of the throttle valve 23. A coil spring 31 surrounds the screw30 and is compressively held between the head of the screw 30 andtheprojection 29 in order to retain screw 30 in adjusted position.

A coil spring 32 which surrounds the outwardly extending portion ofthrottle shaft 24 is engaged atone end with the arm 28 and the other end34 is engaged with the projection 29, the coil spring serving to biasthe throttle valve 23 toward the closed position as shown in FIG. 3.

The upper body 10 is formed at its bottom with an angular boss portion35 and a boss 36 located centrally and an air chamber 37 is defined bythe outer and inner walls of the boss 36 and 35 and communicates througha passage 51 with atmosphere. A flexible member or diaphragm 40 forms awall 39 of the air chamber 37 opposite to the upper wall of the chamber37 and extends across the face of the annular boss portion. An annulargasket 41 is disposed on the opposite face of the diaphragm, as shown inFIGS. 3 and 4. The diaphragm 40 is formed at its center with a hole 42.

Diaphragm 40 is held in place by interposing the peripheral region ofthe diaphragm and the gasket 41 between the boss 35 on the body 10 andan annular boss 46 on a intermediate body 45. The intermediate body 45is formed with an upwardly extending boss 47 opposite to the boss 36 onthe carburetor body 10. An annular spacer 43 is disposed on the topsurface of the diaphragm 40 adjacent the hole 42 and held in placebetween the boss 36 and the center portion of the diaphragm. An annulargasket 44 is disposed on the bottom surface of the diaphragm 40 abovethe boss 47 on the intermediate body 45.

A fuel chamber 48 is defined by the inner and outer walls of the bosses46 and 47 on the intermediate body 45 and the diaphragm 40 forms anupper wall of the chamber 48 opposite to the bottom wall 49 of thechamber 48.

Diaphragm 40 has an annular thin disc 50 and vibrates at a highfrequency to control the admission of fuel into the fuel chamber 48 fordelivery into the mixing passage 11. A diaphragm 54 and a gasket 53 aredisposed between the intermediate body 45 and a pump or lower body 52.

Three bodies 10, 45 and 52 are fixed mutually by screws 55 extendingthrough the bodies 45 and 52 to the annular boss portion 35 of the body10. The lower body 52 is provided with a supplementary fuel chamber 56which is closed by a closure member 57 provided with a nipple portion 58adapted to be connected by a pipe or tube member with a fuel supplytank. The closure member 57 is secured to the lower body 52 by means ofa screw 59 extending into a threaded bore in a central boss portionwhich is provided on the body 52.

A filter screen 60 extends across the supplemental fuel chamber 56 tofilter fuel admitted from inlet 58 into the chamber 56.

A cavity 61 provided on the top of the lower body 52 forms a fuelchamber in conjunction with the diaphragm 54 and a cavity 62 provided onthe underside of the intermediate body 45 forms a pumping or pulsechamber in conjunction with the diaphragm 54. Pumping chamber 62 is incommunication with an opening in an engine crankcase through a passage63.

Fuel filtered through the filter screen 60 is admitted through inletfuel passages 64, 65 and 66 provided in the lower and intermediatebodies 52 and 45 into the fuel chamber 61. A portion of diaphragm 54provides an inlet valve flap 67 disposed between the outlet of thepassage 65 and the inlet of the passage 66. The bottom surface of thebody 45 adjacent the inlet valve flap 67 forms a valve seat 68.

When the diaphragm 54 is moved toward the fuel chamber 62, the valveflap 67 is bent towards the inlet cavity 69 of the passage 66 under theinfluence of reduced pressure developed in the chamber 61 to move awayfrom the valve seat 68 and connect the passage 65 with the passage 66whereby fuel flows into the fuel chamber 61.

When the diaphragm 54 is moved towards the fuel chamber 61, the valveflap 67 is seated on the valve seat 68 thereby interceptingcommunication between the passages 65 and 66; fuel from the chamber 61is transmitted to an outlet fuel passage 70 of body 52. An outlet valveflap 71 is formed on a portion of the diaphragm 54 adjacent the outletof the passage 70 and the upper surface of gasket 53 forms a valve seat72 for the outlet valve flap 71. Valve flap 71 is bendable towardscavity 74 formed at the mouth of a fuel inlet valve 73 belonging to fuelchamber 48 under the influence of the pumping pressure developed in thechamber 61 by the diaphragm 54 thereby connecting the passage 70 withthe valve 73. When the diaphragm 54 is moved towards the pumping chamber62, the valve flap 71 is seated on the valve seat 72 therebyintercepting communication between the passage 70 and the valve 73.

Inlet fuel valve 73 comprises a valve seat member 77 having a fuelpassage 76 and fitted in a bore formed in the body 45 and a ball valveelement 79 located in the recess 78 on the top surface of the seatmember 77 for closing the passage 76. The cavity 74 is defined by aportion of the bore 75 below the seat member 77.

The movement of diaphragm 40 is transmitted to a diaphragm lever 81fixed on a pivot pin 80. The lever 81 has one end engaging the top ofthe valve element 79 and forked ends engaging the underside of thediaphragm disc 50.

An adjusting screw 83 is screwed into a threaded opening provided in thelower body 52 and extends into a bore 82 in the intermediate body 45,the bore 82 being in alignment with the threaded opening.

A compressed coil spring 84 is interposed between the top of the screw83 and the forked ends of the lever 81 to urge the lever 81 towards thediaphragm disc 50.

When the engine is in operation, fuel in the fuel chamber 48 is admittedinto the mixing passage 11 under the influence of reduced pressure oraspiration developed in the mixing passage. When pressure in the chamber48 is reduced, the reduced pressure causes the diaphragm 40 to flex moretowards the chamber 48. Movement of the diaphragm towards the chamber 48causes the lever 81 to be moved around the pivot pin in acounter-clockwise direction as viewed in FIG. 2 against the expansivepressure of the spring 84 whereby the end of the lever 81 movesupwardly, permitting the ball valve element 79 to move away from thevalve seat 77 whereby fuel delivered from the fuel chamber 61 by thepumping action of the diaphragm 54 flows through the passages 70 and 76into the fuel chamber 48.

When fuel pressure in the fuel chamber 48 reaches the predeterminedvalue, the diaphragm 40 is flexed towards the air chamber 37 so that theexpansive pressure of the spring 84 causes the lever 81 to seat thevalve 79 on the valve seat 78 thereby closing the passage 76 andpreventing the flow of fuel into the chamber 48. I

The boss 47 of the intermediate body 45 has a recess 86. Disposed in arecess or chamber 87 formed in the boss 36 of the main body 10 is atubular diaphragm retainer extending through hole 42 of the diaphragm 40into the recess 86. The retainer 85 is fixed at the upper end in ashallow recess 88 formed at the bottom of recess 87. A flange 89 on theretainer 85 is placed interior of the tubular retainer 85. A separatefuel pipe 8 member 91 defining a main fuel passage94 extends coaxiallyto the retainer 85 and is inserted at the upper end into bore 92 on thetop of the retainer 85. The pipe member 91 terminates in the lower endof the retainer 85. A secondary annular fuel inlet passage 93 is definedbetween the retainer 85 and the pipe member 91.

The main fuel passage 94 is in communication with a main fuel dischargeorifice 95 formed in the body and opening into a small venturi 96eccentrically formed 'in the interior of venturi l2. A main fueladjusting screw 97 is threaded into the wall of the body 10 opposite tothe orifice 95 and its rod part 98 extends into the venturi 96 acrossthe mixing passage 11 and has at the lower end the needlepart 99inserted into-the orifice 95. By adjusting the screw vide a fuel and airmixture which flows into the crankcase of the engine through the outletregion 13.

Such an arrangement should be exactly-or approximately given by theformula h W/A;

wherein h is the distance between the center 0 of diaphragm 40and theoutlet point 0 of orifice 95,

A is the effective area of the diaphragm 40,

W is the weight of diaphragm 40,

d) is the specific gravity of fuel. Secondary fuel holes or openings 100are formed on the upper'portion of the diaphragm retainer-85 and thusfuel which flows into the passage 93 from the recess 8.6 is admittedthrough the holes 100. into thecell The fuel feeding system for engineidling and slow speed operation comprises a slow speed orifice 102 andan idling orifice 101 opening into the mixingpassage' 11, as shown inFIGS. 3 and 5.

Holes 101 and 102 are in communication with a supplementary chamber 103and the annular chamber 87 is in communication with the chamber 103through secondary fuel passage 105 in which a jet 104 is disposed.

A secondary fuel adjusting screw 106 screwed into the body 10 has at theupper end a needle portion 107 which is inserted into passage 105 formetering fuel flow through the passage 105 into the chamber 103. A coilspring 110 is disposed around the portion of the screw 106 between thehead 108 and a sealing ring 109.

When the throttle valve 23 is moved to nearly closed or engine idlingposition, fuel is delivered into the mixing passage '11 through theidling orifice 101. When the throttle valve 23 is partially opened fromengine idling position, the low speed orifice 102 begins to deliver fuelfrom the supplemental chamber 103 into the mixing passage in addition tothe fuel delivered through the engine idling orifice 101.

A vapor release passage 111 extends in parallel to the bottom face 49 ofthe fuel chamber 48 within the intermediate body 45 and is incommunication with the bottom of the recess 86. This passage 111 has atits ends portions 112 extending upwardly within the boss 46 and theupper ends of the passage portions are closed by gasket 41. Valve seats113 are defined by the bottom walls of the passage portions andcooperate with check ball valves 114 within the passage portions l02.The upwardly extending passage portions 112 are communicated with thefuel chamber 48 by means of vapor release passages 115 whichextend'laterally from the portions 112 adjacent the valve seats 113.

As seen in FIGS. 2 and 3 of the drawings, when the apparatus is innormal position, the check ball valves 114 are seated on valve seats 113by its their weight to close the passage 111 so that fuel from chamber48 can enter recess 86 only through the fuel inflow hole 90. If fuel inthe chamber 48 is vaporized due to cavitation and percolation, the vaporenters the chamber 86 through the holes together with fuel and isdischarged into the mixing passage 11 through the orifice or orifices101 and 102.

When the apparatus is in positions of slight tilt the same operation asmentioned above will be obtained. When the apparatus is in positions ofextreme tilt or inverted positions, the ball valves 114, as shown inFIG. 7 of the drawings move away from the valve seats 113 until theyreach the gasket 41 and thus fuel in the chamber 48 enters the chamber86 through the holes which are then in the lower position. Meanwhilevapor from fuel in the chamber 48 flows through the passage 115 andpassage 111 into the chamber 86 to discharge through orifice 95 ororifices 101, 102 into the mixing passage 11. As a result, fuel in thefuel chamber 48 will maintain a predetermined level which corresponds tothe necessary amount of fuel for entering the chamber 86 through theholes 90 just after the apparatus returns to normal position.

The aforementioned formula qSh W/A is always applicable in spite ofpositions of extreme tilt or inverted positions because it on the leftwide and W on the right side concurrently replace each others positiveand negativeness. This formula thus ensures the possibility ofcontrolling fuel pressure in the fuel chamber 48 so that the pressure offuel at the orifice 95 will be maintained at a constant value. Orifice95 is positioned on the center axis of diaphragm 40 and thus when theapparatus is moved'around the axis of orifice 95, fuel supplied tomixingpassage 11 from orifice 95 will not be subjected to centrifugal forcethereby ensuring the supply of fuel into mixing passage 11.

The main fuel passage 94 and secondary fuel inlet passage 93 are openedbelow the fuel level in the chamber 86 to prevent air from flowing fromthe orifice 95 throughpassages 94, 93 and into the orifices 101 and 102during engine idling or slow speed operation. Therefore, air will notthin the mixtures during engine idling or slow speed operation. When theengine goes into high speed operation from idling or slow speedoperation, fuel is progressively changed from the flow towards the ports101 and 102 to the flow towards the orifice 95 in response to reducedpressure in the venturi 12 or 96.

We claim:

1. In combination, a fuel feeding apparatus including a body having amixing passage, an air chamber in said body including an upper wall, aflexible diaphragm forming a lower wall of said air chamber, a fuelchamber in a body including a lower wall and an upper wall formed bysaid diaphragm, said diaphragm being actuated by aspiration in saidmixing passage, a second chamber at the center of said fuel chamber forstoring fuel from said chamber, a main fuel discharge orifice andsecondary orifices opening into said mixing passage, two passagesconnecting said second chamber with said orifices, a vapor dischargingpassage connecting said second chamber with said fuel chamber, a valvemeans opening the vapor discharging passage only when the apparatus istilted to extreme positions or inverted, to connect said two chambers.

2. In combination, fuel feeding apparatus including a first body havinga mixing passage, an upper air chamber in said first body including anupper wall, a flexible diaphragm forming a lower wall of the airchamber, a lower fuel chamber in a second body including a lower walland an upper wall formed by said diaphragm, said diaphragm being fixedat its periphery and its center to said two bodies and actuatable byaspiration in said mixing passage, a fuel inlet for said fuel chamber, afuel inlet valve in said fuel inlet, spring loaded means for opening andclosing said valve in response to movement of said diaphragm, a secondchamber in the center portion of said second body for storing fuel fromthe said fuel chamber, a main fuel discharge orifice and secondaryorifices opening into the said mixing passage, and two passagesconnecting the said second chamber with said orifices, said combinationfurther defined by the formula:

h W/A wherein h is the distance between the mouth of the said orificeand the center of the underside of said diaphragm,

A is the effective area of said diaphragm,

W is the weight of said diaphragm,

d) is the specific gravity of fuel.

3. In combination, a fuel feeding apparatus including a first bodyhaving a mixing passage, an upper air chamber in said first bodyincluding an upper wall, a flexible diaphragm forming a lower wall ofsaid chamber, a lower fuel chamber in a second body including a lowerwall and an upper wall formed by said diaphragm, said diaphragm beingfixed at its periphery and its center to said two bodies and actuatableby aspiration in said mixing passage, a fuel inlet for said fuel chambera fuel inlet valve in said fuel inlet, means operable by said diaphragm,but normally for closing said valve, a second chamber in the centerportion of said second body for storing fuel from the top of said fuelchamber, a main fuel discharge orifice and secondary orifices openinginto said mixing passage, and two passages connecting the said secondchamber with said orifices, said main fuel discharge orifice positionedon the center line of said diaphragm.

4. In combination, a fuel feeding apparatus including a first bodyhaving a mixing passage, an upper air chamber in said first bodyincluding an upper wall, a flexible diaphragm forming a lower wall ofsaid air chamber, a lower fuel chamber in a second body including alower wall and an upper wall formed by said diaphragm, said diaphragmbeing fixed at its periphery and its center to said two bodies andactuatable by aspiration in said mixing passage, a fuel inlet valve insaid fuel inlet means operable by movement of said diaphragm, butnormally for closing said valve, a second chamber in the center portionof said second body for storing fuel from said chamber, a main fueldischarge orifice and secondary orifices opening into said mixingpassage, two passages connecting said second chamber with said orifices,a vapor discharging passage connecting said second chamber with saidfuel chamber, and a valve means opening the vapor discharging passageonly when the apparatus is tilted to extreme positions or inverted, toconnect said two chambers.

1. In combination, a fuel feeding apparatus including a body having amixing passage, an air chamber in said body including an upper wall, aflexible diaphragm forming a lower wall of said air chamber, a fuelchamber in a body including a lower wall and an upper wall formed bysaid diaphragm, said diaphragm being actuated by aspiration in saidmixing passage, a second chamber at the center of said fuel chamber forstoring fuel from said chamber, a main fuel discharge orifice andsecondary orifices opening into said mixing passage, two passagesconnecting said second chamber with said orifices, a vapor dischargingpassage connecting said second chamber with said fuel chamber, a valvemeans opening the vapor discharging passage only when the apparatus istilted to extreme positions or inverted, to connect said two chambers.2. In combination, fuel feeding apparatus including a first body havinga mixing passage, an upper air chamber in said first body including anupper wall, a flexible diaphragm forming a lower wall of the airchamber, a lower fuel chamber in a second body including a lower walland an upper wall formed by said diaphragm, said diaphragm being fixedat its periphery and its center to said two bodies and actuatable byaspiration in said mixing passage, a fuel inlet for said fuel chamber, afuel inlet valve in said fuel inlet, spring loaded means for opening andclosing said valve in response to movement of said diaphragm, a secondchamber in the center portion of said second body for storing fuel fromthe said fuel chamber, a main fuel discharge orifice and secondaryorifices opening into the said mixing passage, and two passagesconnecting the said second chamber with said orifices, said combinationfurther defined by the formula: phi h W/A wherein h is the distancebetween the mouth of the said orifice and the center of the underside ofsaid diaphragm, A is the effective area of said diaphragm, W is theweight of said diaphragm, phi is the specific gravity of fuel.
 3. Incombination, a fuel feeding apparatus including a first body having amixing passage, an upper air chamber in said first body including anupper wall, a flexible diaphragm forming a lower wall of said chamber, alower fuel chamber in a second body including a lower wall and an upperwall formed by said diaphragm, said diaphragm being fixed at itsperiphery and its center to said two bodies and actuatable bY aspirationin said mixing passage, a fuel inlet for said fuel chamber a fuel inletvalve in said fuel inlet, means operable by said diaphragm, but normallyfor closing said valve, a second chamber in the center portion of saidsecond body for storing fuel from the top of said fuel chamber, a mainfuel discharge orifice and secondary orifices opening into said mixingpassage, and two passages connecting the said second chamber with saidorifices, said main fuel discharge orifice positioned on the center lineof said diaphragm.
 4. In combination, a fuel feeding apparatus includinga first body having a mixing passage, an upper air chamber in said firstbody including an upper wall, a flexible diaphragm forming a lower wallof said air chamber, a lower fuel chamber in a second body including alower wall and an upper wall formed by said diaphragm, said diaphragmbeing fixed at its periphery and its center to said two bodies andactuatable by aspiration in said mixing passage, a fuel inlet valve insaid fuel inlet means operable by movement of said diaphragm, butnormally for closing said valve, a second chamber in the center portionof said second body for storing fuel from said chamber, a main fueldischarge orifice and secondary orifices opening into said mixingpassage, two passages connecting said second chamber with said orifices,a vapor discharging passage connecting said second chamber with saidfuel chamber, and a valve means opening the vapor discharging passageonly when the apparatus is tilted to extreme positions or inverted, toconnect said two chambers.